Presently, a fixed mullion is the only available method of providing a stop and a seal for adjacent doors in a refrigeration system. With a fixed mullion, the end user's storage space is limited and the loading and unloading of products is hampered.
For instance, in a conventional side-by-side refrigerator, freezer and fresh food compartment doors align along a vertically extending divider wall or mullion, with the mullion extending in a single plane essentially from the top to the bottom of the refrigerator. Although this style of refrigerator has certain advantages over top-mount refrigerators wherein the freezer compartment is arranged vertically above the fresh food compartment, certain disadvantages are also presented. For instance, since the opening provided in a household kitchen for both side-by-side and top-mount refrigerators is essentially standard, top-mount style refrigerators typically have wider shelves in each of the fresh food and freezer compartments as compared to the corresponding shelves in a side-by-side refrigerator.
For this reason, it is often difficult, if not impossible, to accommodate rather wide food items, such as trays, cake pans, platters, turkeys and the like, on a given shelf in the fresh food compartment of a side-by-side refrigerator, while the same item(s) could be readily placed on a corresponding shelf in a top-mount refrigerator. The same is true with respect to the width of the different freezer shelves. For example, it is often difficult to store frozen pizzas and other large food items widthwise in a side-by-side refrigerator freezer compartment, while such items can be easily arranged in the freezer compartment of a top-mount refrigerator. To compensate for this disadvantage, it is not uncommon for owners of side-by-side refrigerators to purchase a second refrigerator for additional food storage space.
In the construction of a refrigerator cabinet, it is typical to include a metal mullion bar positioned between side walls of a horizontally disposed freezer and fresh food compartment or between the top and bottom walls of side-by-side freezer and fresh food compartments. The purpose of the mullion bar or rail is well known to provide support between the side walls of the refrigerator and to provide a load bearing structure about which the liners of the freezer and fresh food compartment are constructed.
The mullion rails or bars are located across the open front of the refrigerator cabinet exposed to the ambient atmosphere and at least a portion of the interior liner of the freezer compartment and/or the fresh food compartment. Typically, the mullion bar provides a structural support to which a partition for the freezer and fresh food compartments are constructed. Since the mullion bar is a metallic material, the mullion is a good heat transfer medium between the ambient atmosphere and the freezer compartment and/or the fresh food compartment. When the ambient air is humid, condensation appears on the face of the mullion bar. To prevent sweating the mullion bar has heater which warms the mullion surface exposed to the ambient air. However these heaters also heat the fresh food compartment and/or freezer compartment raising the energy requirements needed to maintain operation of the refrigerator.
The mullion bar also provides a reinforced surface against which the doors may close. The door includes a gasket having magnets which are attracted to the metal mullion bar to effect a seal against the mullion bar. Thus the mullion bar is required to provide an effective seal against the door gaskets which must withstand the stresses of repeated door closure and provide a magnetic attracting medium.
Present manufacturers of ultra low temperature refrigerated equipment utilize interior access doors to help with temperature control and reduce the migration of cold air out of the unit. The problem that exists with interior access doors is that with extended lengths, manufacturers are faced with structural and thermal concerns. A longer door gives a moment arm, which can deform or crack hinge surfaces over time. Along with these structural issues there is also the thermal movement of the door. Thermal movement is due to the coefficient of linear expansion. The growth/shrink of the interior access door is proportional to its length, change in temperature and selection of material used.
For example, a typical response of a 39 inch long inner access door manufactured from ABS plastic will have thermal movement relative to the following formula:Change in Length(in.)=Length at Ambient(in.)×Coeff. of Expansion×10−6×Change in Temp (° F.)For example,Change in Length(in.)=39×53×10−6×200.8° F.Change in Length(in.)=0.41505
Presently, manufacturers either limit the inner access door length or utilize a fixed mullion to divide the required length by two. The use of a fixed mullion will limit accessibility while adding considerable cost to both the consumer and the manufacturer.
A need therefore exists for a refrigerator that will allow full access to larger chambers without affecting interior temperature or damaging the interior by deformations.